The limestone grinding process involves mining, crushing, and processing natural limestone ore into industrial raw materials of various specifications. It is widely applied in construction, building materials, chemicals, and metallurgy.
Limestone Characteristics and Applications
Chemical composition: Mainly calcium carbonate (CaCO₃), with small amounts of magnesium oxide, silica, and other impurities.
Main applications:
- Construction materials: Cement, concrete aggregates, lime.
- Chemical raw materials: Paper-making, plastic fillers, desulfurization agents.
- Metallurgy: Used as a flux in steelmaking.
Limestone Mining Process
Overburden Stripping
- Bulldozers or excavators clear vegetation, soil, and weathered rock from the deposit surface to expose fresh ore layers.
Blasting Operations (for open-pit mining)
- Drilling: Blast holes are drilled using down-the-hole drills or rock drills, with depth and spacing adjusted to ore hardness.
- Charging and blasting: Explosives are loaded, and detonation systems set up, following safety procedures. Blasting breaks ore into manageable sizes.
- Safety: Danger zones are defined, personnel and equipment evacuated, and post-blast checks ensure no misfires remain.
Ore Excavation and Loading
- Excavators or loaders load blasted ore into dump trucks for transport to the crushing plant.
- Oversized boulders (>1.5m) are secondarily broken (e.g., with hydraulic hammers) for easier handling.
Crushing and Processing
Primary Crushing
- Goal: Reduce raw ore (300–1500mm) to 100–300mm.
- Equipment:
- Jaw Crusher: Simple structure, large crushing ratio, wear-resistant; suitable for hard limestone.
- Gyratory Crusher: Large capacity, high automation; used in large-scale mining.
- Process: Ore fed via vibrating feeder, crushed by compression between moving and fixed jaws, then conveyed by belt to the next stage.
Secondary Crushing
- Goal: Reduce product to 30–100mm.
- Equipment:
- Cone Crusher: Crushing through compression between moving and fixed cones; produces well-shaped aggregates.
- Impact Crusher: High-speed rotor strikes ore; high reduction ratio, suitable for limestone with low impurities.
- Screening: Crushed materials screened by vibrating screens; oversized particles return for re-crushing.
Fine Crushing and Grinding
- Fine crushing: Reduce ore to 5–30mm for construction aggregates.
- Equipment:
- VSI Impact Crusher (Sand Maker): “Rock-on-rock” principle; produces cubical aggregates.
- Grinding: Ore processed to 0.074–1mm (e.g., 200 mesh) for lime powder, calcium powder, etc.
- Ball Mill with Classifier: Suitable for medium–low hardness ores; output 3–30 t/h.
- Vertical Roller Mill: Energy-efficient, large-scale, integrates drying and grinding.
Screening and Classification
- Vibrating screens separate crushed material into size fractions (e.g., 5mm, 10mm, 20mm); oversize returns for further crushing.
- Air classifiers separate fine powder from coarse particles after grinding, ensuring uniform product fineness (e.g., 325 mesh, 800 mesh).
Deep Processing and Purification (as required)
Calcination (for quicklime production)
- Crushed limestone fed into shaft kilns or rotary kilns, calcined at 900–1200°C to produce calcium oxide (CaO) and CO₂.
- Equipment: Energy-saving shaft lime kilns, capacity 50–500 t/d.
Wet Grinding (for hydrated lime)
- Quicklime reacts with water to form calcium hydroxide (slaked lime), then processed via wet grinding, filtration, and drying to produce superfine Ca(OH)₂ powder.
Purification (for high-purity applications)
- Washing: Removes clay and surface impurities.
- Magnetic separation/flotation: Removes Fe, Mg impurities, raising CaCO₃ purity (>98% for food- and pharma-grade limestone).
Environmental Protection and Safety
Dust Control
- Crushing and screening machines enclosed with dust collectors (≤30mg/m³ emission).
- Stockpiles covered with dust nets, transport trucks tarped, roads sprayed with water.
Noise Control
- Low-noise equipment, soundproof enclosures for crushers, green buffer zones; noise ≤65 dB (daytime).
Wastewater Treatment
- Washing water treated in sedimentation tanks and reused; suspended solids removal >90%, meeting industrial recycling standards.
Safety Management
- Blasting strictly follows safety codes; operators use PPE (masks, earplugs); equipment regularly inspected for overload prevention.
Epic Powder
The limestone grinding process is a complete chain from mining to fine powder preparation, covering crushing, grinding, classification, deep processing, and environmental protection. With over 20 years of expertise in ultrafine powder grinding, classification, and processing, Epic Powder provides customized limestone grinding solutions. From ball mill classification lines to vertical mills and advanced classifiers, Epic Powder ensures high efficiency, stable quality, and eco-friendly production, helping customers achieve maximum value from limestone resources.